Re: [Qemu-devel] [PATCH 05/10] include: add spinlock wrapper

["Alex Bennée" <alex.bennee@linaro.org>]

Paolo Bonzini <pbonzini@redhat.com> writes:

> On 05/04/2016 07:30, Emilio G. Cota wrote:
>> Wrap pthread_spin on POSIX, or QemuMutex on Windows.
>>
>> AFAIK there are is no off-the-shelf spinlock implementation for
>> Windows, so we'll just use QemuMutex.
>
> It's much simpler to use a simple test-and-set spinlock.
>
> GitHub is down, but this should be the link
> http://github.com/bonzini/qemu/commit/e1361634 (it's in my mttcg
> branch).

In addition this version breaks on the OSX/clang build:

https://travis-ci.org/stsquad/qemu/jobs/121002991

>
> Paolo
>
>> Signed-off-by: Emilio G. Cota <cota@braap.org>
>> ---
>>  include/qemu/spinlock-posix.h | 60 +++++++++++++++++++++++++++++++++++++++++++
>>  include/qemu/spinlock-win32.h | 33 ++++++++++++++++++++++++
>>  include/qemu/spinlock.h       | 10 ++++++++
>>  3 files changed, 103 insertions(+)
>>  create mode 100644 include/qemu/spinlock-posix.h
>>  create mode 100644 include/qemu/spinlock-win32.h
>>  create mode 100644 include/qemu/spinlock.h
>>
>> diff --git a/include/qemu/spinlock-posix.h b/include/qemu/spinlock-posix.h
>> new file mode 100644
>> index 0000000..51c2c08
>> --- /dev/null
>> +++ b/include/qemu/spinlock-posix.h
>> @@ -0,0 +1,60 @@
>> +#ifndef QEMU_SPINLOCK_POSIX_H
>> +#define QEMU_SPINLOCK_POSIX_H
>> +
>> +#include <qemu/thread.h>
>> +#include <qemu/osdep.h>
>> +
>> +typedef pthread_spinlock_t QemuSpinLock;
>> +
>> +static inline void qemu_spinlock_error_exit(int err, const char *msg)
>> +{
>> +    fprintf(stderr, "qemu: %s: %s\n", msg, strerror(err));
>> +    abort();
>> +}
>> +
>> +static inline void qemu_spinlock_init(QemuSpinLock *lock)
>> +{
>> +    int rc;
>> +
>> +    rc = pthread_spin_init(lock, PTHREAD_PROCESS_SHARED);
>> +    if (unlikely(rc)) {
>> +        qemu_spinlock_error_exit(rc, __func__);
>> +    }
>> +}
>> +
>> +static inline void qemu_spinlock_destroy(QemuSpinLock *lock)
>> +{
>> +    int rc;
>> +
>> +    rc = pthread_spin_destroy(lock);
>> +    if (unlikely(rc)) {
>> +        qemu_spinlock_error_exit(rc, __func__);
>> +    }
>> +}
>> +
>> +static inline void qemu_spinlock_lock(QemuSpinLock *lock)
>> +{
>> +    int rc;
>> +
>> +    rc = pthread_spin_lock(lock);
>> +    if (unlikely(rc)) {
>> +        qemu_spinlock_error_exit(rc, __func__);
>> +    }
>> +}
>> +
>> +static inline int qemu_spinlock_trylock(QemuSpinLock *lock)
>> +{
>> +    return pthread_spin_trylock(lock);
>> +}
>> +
>> +static inline void qemu_spinlock_unlock(QemuSpinLock *lock)
>> +{
>> +    int rc;
>> +
>> +    rc = pthread_spin_unlock(lock);
>> +    if (unlikely(rc)) {
>> +        qemu_spinlock_error_exit(rc, __func__);
>> +    }
>> +}
>> +
>> +#endif /* QEMU_SPINLOCK_POSIX_H */
>> diff --git a/include/qemu/spinlock-win32.h b/include/qemu/spinlock-win32.h
>> new file mode 100644
>> index 0000000..5a105fb
>> --- /dev/null
>> +++ b/include/qemu/spinlock-win32.h
>> @@ -0,0 +1,33 @@
>> +#ifndef QEMU_SPINLOCK_WIN32_H
>> +#define QEMU_SPINLOCK_WIN32_H
>> +
>> +#include <qemu/thread.h>
>> +
>> +typedef QemuMutex QemuSpinLock;
>> +
>> +static inline void qemu_spinlock_init(QemuSpinLock *lock)
>> +{
>> +    qemu_mutex_init(lock);
>> +}
>> +
>> +static inline void qemu_spinlock_destroy(QemuSpinLock *lock)
>> +{
>> +    qemu_mutex_destroy(lock);
>> +}
>> +
>> +static inline void qemu_spinlock_lock(QemuSpinLock *lock)
>> +{
>> +    qemu_mutex_lock(lock);
>> +}
>> +
>> +static inline int qemu_spinlock_trylock(QemuSpinLock *lock)
>> +{
>> +    return qemu_mutex_trylock(lock);
>> +}
>> +
>> +static inline void qemu_spinlock_unlock(QemuSpinLock *lock)
>> +{
>> +    qemu_mutex_unlock(lock);
>> +}
>> +
>> +#endif /* QEMU_SPINLOCK_WIN32_H */
>> diff --git a/include/qemu/spinlock.h b/include/qemu/spinlock.h
>> new file mode 100644
>> index 0000000..001b55e
>> --- /dev/null
>> +++ b/include/qemu/spinlock.h
>> @@ -0,0 +1,10 @@
>> +#ifndef QEMU_SPINLOCK_H
>> +#define QEMU_SPINLOCK_H
>> +
>> +#ifdef _WIN32
>> +#include "spinlock-win32.h"
>> +#else
>> +#include "spinlock-posix.h"
>> +#endif
>> +
>> +#endif /* QEMU_SPINLOCK_H */
>>


--
Alex Bennée